Method of forming undercut die castings



Aug. 26, 1947., L. H. MORIN 7 2,426,403

I METHOD OF FORMING UNDERCUT DIE CASTINGS Filed July 22. 1944 IN TOR vLon/As" .NoR/N B ATTORNEY Patented Aug. 26, 1947 METHOD OF FORMING UNDERCUT DIE CASTINGS Louis H. Morin, Bronx, N. Y., assignor of onehalf to Davis Marinsky, New York, N. Y.

Application July 22, 1944, Serial No. 546,180

1 Claim. (Cl. 18-55) This invention relates to the formation of undercut die castings by the movement 01- dies angularly with respect toeach other in directions to free the dies from undercut portions of the castings. More particularly, the invention relates to the formation of castings or groups of castings on a mounting member such, for example, as the formation of scoops along one edge of a separable fastener stringer, wherein undercut or recessed surfaces in the scoops may be formed and the castings removed from the dies employed by movement of the dies or at least one of said dies at an angle other than a perpendicular to the adjacent surfaces of the dies or in moving the dies angularly with respect to each other.

The novel features of the invention will be best understood from the following descriptions when taken together with the accompanying drawing, in which certain embodiments of the invention are disclosed, and in which the separate parts are designated by suitable reference characters in each of the views and in which:

Fig. l is a side and sectional view of a part of two stringers with a slider arranged thereon showing scoop castings on the stringers made according to the method herein described.

Fig. 2 is a perspective view of one of the scoops shown detached with respect to a stringer.

Fig. 3 is a face view of one die part indicating the manner of forming two scoops simultaneously on the beaded edge of a stringer tape.

Fig. 4 is a sectional plan view substantially on the line 4-4 of Fig. 3.

Fig. 5 is a diagrammatic sectional view on the line 55 of Fig. 3 and omitting background illus'trations.

Fig, 6 is a view similar to Fig. 5 showing both dies in a partially open position; and p Fig. 7 is a view similar to Figs. 5 and 6 showing the dies fully open and indicating the tape of a stringer in the background and also indicating the grippers employed to support and feed the tape withthe castings thereon relatively to the dies.

In the art of forming die castings between a pair of relatively movable dies, it has been the common practice to movethe dies toward and from each other in the sameplane or in-a direction normal to the parting line of the dies. In this method of procedure, it has been impossible to form undercuts in the castings, except through the medium of cores or other independently movpractice, I have conceived a method of forming undercuts in castings by operating or moving the dies angularly to each other or angularly to the parting line of the dies in order to clear the dies of the undercut surfaces on the castings and permit free removal of the castings from the dies. Further, this result is accomplished without, the use of cores or other relatively movable members otherwise employed to form undercut portions or surfaces in castings of the kind under consideration.

While my invention is generally applicable to the art of forming die castings of any type and kind and of metal or plastic materials, for the purpose of illustrating one adaptation and use of the invention, the method is shown in the production of what I term coreless scoops of separable fastener stringers, wherein the undercut portion of the casting is defined by a channeled or recessed surface on'one surface of the scoop and extending longitudinall thereof with the deepest portion of the channel arranged along, or substantially along, the parting line of the dies employed in forming such die cast scoops. It will be apparent, however, that this method, which is illustrated in the formation of scoops, may be applied to forming castings of many types and kinds whether the castings are formed singly or in multiple. The present illustration shows the formation of two similar scoops simultaneously upon the stringer of a fastener tape.

To illustrate the type of devices or products produced accordin to the method herein described, I have shown in Fig. 1 of the drawing at In and II portions of two stringers, upon the beaded edges l2 and I3 of which are arranged what I term coreless scoops [4, all of which are of the same general form and are substantially V-shaped in cross-sectional form, as will appear in Fig. 5 of the drawing. The scoops have channels l5 extending on one surface thereof and corresponding ridges IS on the other surface thereof. In Figs. 3, 5, 6 and 7, the scoops are shown in a position inverted with respect to the position shown in Figs. 1 and 2, butthe actual position of the scoops, as they will appear in the dies with respect to what may be a top.

or bottom is immaterial and, insofar as Fig. 1 is concerned, this is simply a use of the stringers and, here again, it is immaterial whether the channels are directed upwardly or downwardly, in that the scoops are of a double action type and can be coupled and uncoupled with a slider arranged in the position shown in Fig. l or in a position reversed thereto. r

As above stated, the scoops l4 are of the double action type and include, at their outer coupling ends, opposed projections Ill and I8, the projections I! being on the channeled side l5 and the projections E8 on the ridged side iii of the scoops. These projections are continuous through the scoop, excepting that the walls of the scoop taper toward the side surfaces in the manner illustrated in Figs. 5, 6 and 7 of the drawing and this tapering is primarily to provide clearances between adjacent coupled scoops, as seen at [9 of Fig. 1 of the drawing, for free bending of the stringers one upon the other.

Inwardly of the projections H and E8, the scoops have transverse recesses 25 and 21 again arranged on the channeled sides l5 and ridged sides l6, respectively of the scoops and of a contour to receive the projections I? and IQ of the scoops of a companion stringer, as illustrated in Fig. 1 of the drawing. The scoops are cast directly on the beaded edges l2, 13 of the stringers and this forms, at the attaching end of the scoops, apertures 22, as indicated in Fig. 2 of the drawing which envelop the tape edges. It will be apparent that the channels it and ridges it retain the scoop against transverse separation one with respect to the other, whereas the projections 11 and i8 and recesses 28, 2! retain the scoops against lateral separation.

In forming the scoops I4, I have illustrated in the accompanying drawing, the simultaneous formation of a pair of such scoops at .spaced intervals upon the beaded edge of a stringer tape. However, one or more of the scoops may be .so formed and, in Figs. 5, 6 and '7, I have diagram matically illustrated at 23 and 2 3 a pair of dies which are arranged angularly to each other and have a pair of similar cavities 25 and 26 on adjacent'surfaces thereof which, when they abut, define the parting line 2'! of the dies. Opposed walls of each of the cavities 25, 26 have, as seen in Figs. '5, 6 and 7, opposed upper and lower surfaces 28 and 29 which converge inwardly to the base of the cavity. These surfaces 28 and 29 define the 'V-shape cross-sectional contour of the scoops M in registration of the cavities 25, 2-6 one with the other. The dies 23 and 24 are shown in Fig. 5 in full lines in abutting relationship to each other or, in otherwords, in the position assumed thereby in simultaneously forming the pair of casting-s i l by injection of casting material through a gate passage 3!! on the parting line of the dies, note Fig. 3, from a suitable nozzle 3!. The gate passage 38 has branches 32 and 33 extending to each individual cavity, as will be apparent.

I-nFig. 6 of the drawing, the dies 23 and 2 3 are shown in a partially open position;.whe-reas in Fig. both dies are shown in a fully open position and, when in such position, the stringer engaged by a pair of grippers 34 is moved relatively to the diesit and i i to feed the pair of cast scoops J 5 thereon out of the path of movement of the dies, as is indicated in dotted lines in Fig. 7 of the drawing to bring the next'successive. portion of the stringer tape in position to receive-the next pair of die cast scoops and this operation is continued until the desired scoop lengths are provided on the stringer. Then by suitable means a long movement of the stringer may be provided to widely space groups of stringers along the tape in forming what are commonly referred to as stringer lengths.

Inthe operation of separating the dies 23 and 24, they are moved in a direction parallel to' or clearing the surfaces 28 of the cavities 25 and 26 and the surfaces 29 will thus become free of the casting as the dies are separated, as will clearly appear from a consideration of Figs. 6 and '7. It is immaterial which surface is followed by the dies in movement over the castings in the separation of the dies and, in fact, by holding the stringer tape stationary, between the grippers 34, the dies could actually be moved free of both upper and lower surfaces of the casting by controlling the angular movement of the dies away from each other, in a manner to clear both of said upper and lower surfaces.

In separating the dies, one die may be moved a slight distance into open position, while the other die remains stationary and then the said other die moved slightly to automatically free or eject the castings from the die cavities. Another way of expressing this operation would be to say that one die starts its opening movement slightly in advance of the companion die.

As the V-shaped cross-sectional contour shown in Figs. 5, 6 and 7 is carried throughout the entire length of each scoop and varies only as to thickness at the different cross-sections of the scoop, there is no surface which prevents the free movement of the dies away from each other, as indicated in Figs. 6 and! of the drawing. This inability to separate would prevail if the upper and lower surfaces of the scoops, at each side of the longitudinal center thereof, had parallel angular walls rather than the outwardly converging walls, as indicated. These converging walls are desirable in producing the clearances in the resulting fastener and will also provide a freer displacement of the casting from the cavities 25 and 26 of the dies 23 and 24.

In Fig. 1 of the drawing, I have indicated at 3-5 a slider for coupling and uncouplin the stringers, the slider being of conventional construction and comprising spaced walls, one of which is shown at 36 and these walls are joined by a connecting web 31 centrally of the wide end of the slider. At .38 are shown the inturned side flanges for engaging the scoops, as in other devices .of' this kind. In Fig. 1, the narrow end 39 of the. slider is directed downwardly and, in the above referred to double action use of the scoops, this end 39 may be directed upwardly. In fact, in some instances, two sliders are movable along the stringers with the narrow ends of the sliders adjacent or with the wide ends of said sliders adjacent on the stringers.

From the foregoing, it will appear that, in the successive steps of the method of forming castings of the kind unde consideration, the dies 23 and 24 are first moved into closed position, as indicated in Fig. 5 with the cavities .25 and 26 in registering alinement and adjacentsurfaces of the dies abutting on the parting line 27. Then heated casting material is pressure injected into the cavities in forming the pair of cast scoops on the beaded edge of the stringer which is arranged in the cavities of the dies, as will clearly appear in Fig. 4 of the drawing; at which time, the grippers 34 are firmly engaging the stringer tape adjacent the dies. Upon completing the injection of casting material intothe cavities, the dies are.

then separated by first moving one die slightly until the castings are clear of the cavitiesyas seen in Fig. 7 of the drawing. The finished castings are then moved out of the path of the dies, another section of the stringers brought into position between the dies, after which the dies are again closed and the above operation is repeated.

It will be understood that, with the formation of various types and kinds of castings having undercut portions, at least in parts of the castings, the dies will be moved relatively to each other in an angular direction to free the dies from at least the undercut portion of the castings by moving the dies parallel to or clear of the wall forming the undercut or in a direction freeing the cavities of the dies from the undercut and otherwise forming the casting to prevent any interference with such angular movement of the die in freeing the casting. In this respect, it is important to bear in mind that surfaces throughout the length of the casting must not extend transversely in a manner to interfere with or establish any locking relationship of the casting in the die cavity. Clearly, it may not be sufficient to insure free withdrawal of the die that it be so formed as to clear the casting as viewed in some one particula cross-section. It must clear every cross-sectional form of the castin and by one and the same angular movement. In the present showing and by way of illustration, the projections I1 and I8 and the recesses 20 and 2| extend straight across the casting from the low and high points defined by the channel l5 and rid e l6 and form no resistance or obstruction whatever to a free lateral and opposed movement of the dies relatively to each other. Failure to have clearances for free separation of the dies along the lines above outlined would produce an inoperative structure or, in other words, a structure wherein the castings would be locked in the 'dies and the only method of removing the castings would be to completely destroy the dies.

My improved method will lend itself to the production of undercut die castings of many types and kinds and it must be borne in mind that it will not be essential in all cases that both dies be moved angularly, i. e. other than normal to the parting line of the dies. In some instances, the undercuts may be disposed at one side only of the casting and may then be freed by angular movement of one die only, whereas in other instances the undercuts may be extended in different directions at opposedsides of a casting and, in such instances, the dies will be moved accordingly. From this standpoint, it may be said that the dies or each die part is moved at an angle to clear an undercut portion of a part of a casting formed by the die.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent is:

The method of forming die cast scoops of separable fastener stringers having undercuts on one surface thereof, which comprises injecting casting material into a cavity of a pair of dies in forming a scoop in said cavity having diverging walls defining an undercut recess extending throughout the full length of one surface of said scoop and the other surface of said scoop having walls converging with respect to the first named walls to side edges of the scoop, then separating the dies by movement of each die in a direction paralleling the walls on at least one surface of the scoop, supporting'the cast scoop intermediate the dies in the separation of said dies, and moving one die in advance of the other die in initial separation of the dies in ejecting the casting from the dies.

LOUIS H. MORIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,227,265 Lauterbach Dec. 31, 1940 1,370,192 Crate Mar. 1, 1921 2,224,980 Morin Dec. 17, 1940 2,322,908 Poux June 29, 1943 

